Problems between my girlfriend and EX Wife?

My girlfriend Kagney and my EX wife Stacy hate one another. Kagney wants us to move to Colorado where she is from. I don't want to leave Ohio and neither does Stacy especially since i would not only be leaving my family and friends but my 6 year old daughter. Stacy told me if i move she will fight for sole custody. Kagney told me i can still see my daughter she understands how important she is and how much i love her. Stacy told me Kagney is selfish and immature. Kagney believes Stacy still has feelings for me. They have got into psychical fights and arguments and stuff. What should i do?